Compressive stress-strain relationship of steel fiber-reinforced reactive powder concrete after exposure to elevated temperatures

An experimental research is performed on the complete compressive stress-strain relationships for reactive powder concrete (RPC) with various steel fiber contents after exposure to 20-900°C. The steel fiber volume dosage is 1%, 2% and 3%. The results indicate that the compressive strength and elastic modulus of RPC increase at first, then decrease with the increasing temperature, and the loss of elastic modulus is quicker than the compressive strength. The peak strain and ultimate strain reach peaks at 600°C and 700°C respectively, and they increase exponentially before the peak points, but decrease linearly after the peak points. Based on the experiment results, the compressive stress-strain constitutive equations applicable to the unheated and heated RPC are proposed, which provide a valuable reference for future industrial applications and design.